CN113013942A - Negative voltage clamping circuit and lithium battery protection circuit comprising same - Google Patents

Negative voltage clamping circuit and lithium battery protection circuit comprising same Download PDF

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Publication number
CN113013942A
CN113013942A CN202110224474.4A CN202110224474A CN113013942A CN 113013942 A CN113013942 A CN 113013942A CN 202110224474 A CN202110224474 A CN 202110224474A CN 113013942 A CN113013942 A CN 113013942A
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China
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voltage
coupled
detection port
operational amplifier
charger
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CN202110224474.4A
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Chinese (zh)
Inventor
王一鹏
成杨
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Sino Wealth Microelectronics Co ltd
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Sino Wealth Microelectronics Co ltd
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Priority to CN202110224474.4A priority Critical patent/CN113013942A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00302—Overcharge protection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M10/4257—Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00308—Overvoltage protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Secondary Cells (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention provides a negative voltage clamping circuit and a lithium battery protection circuit comprising the same. The negative voltage clamping circuit comprises a PMOS tube, a first resistor and an operational amplifier. When the positive input end of the operational amplifier detects that the voltage value of the charger detection port of the lithium battery protection circuit is smaller than the voltage of the ground end of the lithium battery protection circuit, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end.

Description

Negative voltage clamping circuit and lithium battery protection circuit comprising same
Technical Field
The invention relates to the field of simulation integrated circuits, in particular to a lithium battery protection circuit.
Background
In the lithium battery protection circuit chip, in order to ensure that a PIN (PIN) is not lower than a grounding PIN (GND PIN) of the circuit by more than 0.7V, a negative pressure clamping circuit is required to be added to ensure the PIN. The negative voltage clamp circuit is usually arranged between the GND PIN of the lithium battery protection circuit chip and a charger detection port (CGRD PIN) where negative voltage is possibly seen.
However, conventional negative voltage clamp circuits have safety concerns. In particular, when the charger is still connected in the battery pack over-voltage protection state, the clamping current of the negative voltage clamping circuit can still charge (i.e., trickle charge) the battery pack, which can cause safety problems and even explosion risks in the battery pack protection scheme when the duration is long or the charger voltage is significantly higher than the battery pack voltage.
Therefore, a need exists for a safer negative voltage clamp that solves the problem of trickle charge.
Disclosure of Invention
The present invention overcomes the trickle charge problem mentioned above by providing a novel negative voltage clamp circuit.
The negative voltage clamp circuit includes: PMOS pipe, first resistance and operational amplifier.
The lithium battery protection circuit is provided with a positive power source end, a grounding end, an external input voltage end and a charger detection port; one end of the first resistor is coupled with the detection port of the charger, and the other end of the first resistor is coupled with the external input voltage end; the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is smaller than the voltage of the ground end, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is greater than the voltage of the ground end, the output end of the operational amplifier controls the PMOS tube to be closed, and the negative voltage clamping circuit does not clamp the charger detection port and does not influence the normal work of the charger detection port.
In one embodiment, a battery pack may be coupled between the positive power terminal and the ground terminal, and a charger may be coupled between the positive power terminal and the external input voltage terminal; the clamp current is sourced from the positive power supply terminal to ensure that no charging current is generated to the battery pack.
In one embodiment, the resistance of the first resistor is selected according to the most negative voltage of the external input voltage end, so that the maximum current flowing through the first resistor does not exceed the maximum current endurance of the PMOS transistor.
In one embodiment, the size of the PMOS transistor is selected according to the driving capability, so that when the detection port of the charger is under negative voltage, the PMOS transistor provides current flowing through the first resistor, and the negative feedback loop can be guaranteed to work normally.
The invention also provides a lithium battery protection circuit.
The lithium battery protection circuit is provided with a positive power supply terminal, a grounding terminal, an external input voltage terminal and a charger detection port, wherein the positive power supply terminal and the external input voltage terminal are coupled with a charger, and the positive power supply terminal and the grounding terminal are coupled with a battery pack.
The lithium battery protection circuit comprises a negative voltage clamping circuit, and the negative voltage clamping circuit comprises: PMOS pipe, first resistance and operational amplifier.
One end of the first resistor is coupled with the detection port of the charger, and the other end of the first resistor is coupled with the external input voltage end; the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is smaller than the voltage of the ground end, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is greater than the voltage of the ground end, the output end of the operational amplifier controls the PMOS tube to be closed, and the negative voltage clamping circuit does not clamp the charger detection port and does not influence the normal work of the charger detection port.
In one embodiment, the clamp current is sourced from the positive power supply terminal to ensure that no charging current is generated to the battery pack.
In one embodiment, the resistance value of the first resistor is selected according to the most negative voltage of the external input voltage terminal PACKN, so that the maximum current flowing through the first resistor does not exceed the maximum current tolerance of the PMOS transistor.
In one embodiment, the size of the PMOS transistor is selected according to the driving capability, so that when the detection port of the charger is under negative voltage, the PMOS transistor provides current flowing through the first resistor, and the negative feedback loop can be guaranteed to work normally.
The invention also provides a lithium battery protection circuit.
The lithium battery protection circuit is provided with a positive power supply terminal, a grounding terminal, an external input voltage terminal and a charger detection port, wherein the positive power supply terminal and the external input voltage terminal are coupled with a charger, and the positive power supply terminal and the grounding terminal are coupled with a battery pack;
the lithium battery protection circuit comprises a negative voltage clamping circuit, and the negative voltage clamping circuit comprises: feedback circuit, clamping circuit and first resistance.
The first resistor is coupled between the external input voltage terminal and the charger detection port.
The negative feedback circuit detects the voltage value of the detection port of the charger, and when the voltage value is lower than the voltage of the ground end, the negative feedback circuit outputs a clamping control signal to control the clamping circuit to generate clamping current.
The clamping circuit is coupled between the positive power supply end and the charger detection port, and generates the clamping current after receiving the clamping control signal of the negative feedback circuit, so that a voltage drop is formed on the first resistor, and the voltage of the charger detection port is clamped to the voltage of the ground end, so that the charger detection port is ensured not to generate negative voltage.
In one embodiment, the feedback circuit comprises a PMOS transistor. The clamping circuit comprises an operational amplifier. The grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
The negative voltage clamping circuit and the lithium battery protection circuit IC integrated with the negative voltage clamping circuit clamp external negative voltage by using a negative feedback technology, and simultaneously clamp current is extracted from a power supply, so that trickle charging current is reduced while the lithium battery protection circuit IC is not influenced by the negative voltage.
Drawings
The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. It is to be noted that the appended drawings are intended as examples of the claimed invention. In the drawings, like reference characters designate the same or similar elements.
FIG. 1 shows the connection relationship of a negative voltage clamp circuit in a lithium battery protection circuit chip in the prior art;
FIG. 2 illustrates a negative voltage clamp circuit according to an embodiment of the present invention;
fig. 3 shows a topology of a negative voltage clamp circuit according to an embodiment of the invention.
Detailed Description
The detailed features and advantages of the present invention are described in detail in the detailed description which follows, and will be sufficient for anyone skilled in the art to understand the technical content of the present invention and to implement the present invention, and the related objects and advantages of the present invention will be easily understood by those skilled in the art from the description, claims and drawings disclosed in the present specification.
Fig. 1 shows a connection relationship of a Negative voltage clamp circuit (Negative voltage clamp circuit) in a lithium battery protection circuit chip (hereinafter, referred to as an IC) in the related art. As shown in fig. 1, when the battery pack is overcharged and the lithium battery protection circuit chip enters overvoltage protection to turn off SW, thereby cutting off the charging path, the charging path outside the lithium battery protection circuit chip is cut off. Since the charger voltage is higher than the battery pack voltage, the voltage at the charger detection port (CGRD terminal) is lower than the ground terminal (GND) voltage, i.e., a negative voltage appears in the CGRD PIN.
At this time, the Negative voltage clamp circuit (Negative voltage clamp circuit) starts operating, and the clamp current I is drawn from the GND portCGRAt the resistance R1A voltage drop is formed, and the voltage of the detection port (CGRD end) of the charger is clamped to be close to 0V, so that the CGRD PIN is ensured not to see negative voltage.
ICGRAs a clamping current, the battery pack is also provided with a charging current, so that when the battery pack is overcharged to enter an overvoltage protection state, the charging current continues to charge the battery pack (i.e., trickle charge), and when the charging current lasts for a long time or the charger voltage is significantly higher than the battery pack voltage, the battery pack protection scheme may cause a safety problem or even an explosion risk.
In order to overcome the trickle charge problem mentioned above, the present invention provides a novel negative voltage clamp circuit and a negative voltage clamp method. The circuit and the method utilize the IC power supply to provide clamping current for the negative voltage clamping circuit, thereby well solving the problem of trickle charge generated when the charger is still connected in an overvoltage protection state of a lithium battery protection system.
Figure 2 illustrates a negative voltage clamp circuit according to an embodiment of the present invention. The negative voltage clamp circuit includes a negative feedback circuit 201, a clamp circuit 202, and a first resistor R1.
The first resistor R1 is a current limiting resistor coupled between the negative terminal of the charger (i.e., the external input voltage terminal PACKN) and the charger detection port (CGRD terminal).
The negative feedback circuit 201 detects a voltage value of a CGRD pin of a lithium battery protection circuit chip (hereinafter referred to as an IC), and when the voltage value of the CGRD pin is lower than a ground voltage (i.e., 0V), the negative feedback circuit 201 detects that the voltage value of the CGRD pin is lower than the ground voltageOutputs a clamping control signal to the clamping circuit 202 to control the clamping circuit 202 to generate a clamping current (I)CGR)。
The clamping circuit 202 is coupled between a positive power supply terminal VDD of the lithium battery protection circuit chip and a CGRD pin of the battery protection circuit chip. The clamp circuit 202 generates a clamp current (I) upon receiving a clamp control signal from the negative feedback circuit 201CGR) A voltage drop is formed across the first resistor R1 clamping the voltage at the CGRD pin near 0V, thereby ensuring that the charger sense port (CGRD port) does not see a negative voltage.
Since the clamp 202 operates between the positive supply terminal VDD voltage and the charger detection port (CGRD terminal), ICGRIs extracted from VDD, and does not generate trickle charge to the battery pack, thereby ensuring that no trickle charge current is generated when the IC is in an overcharge protection state, namely solving the problems in the prior art.
Fig. 3 shows a topology of a negative voltage clamp circuit according to an embodiment of the invention. The negative voltage clamp circuit comprises an operational amplifier OP1, a PMOS transistor M1 and a resistor R1. The PMOS tube M1 is coupled between the working power supply VDD of the lithium battery protection circuit chip and the CGRD pin of the battery protection circuit chip. The output terminal OPO of the operational amplifier OP1 is coupled to the gate of the PMOS transistor M1. The negative input terminal of the operational amplifier OP1 is coupled to ground GND, and the positive input terminal is coupled to the charger detection port (CGRD terminal). The resistor R1 is a current limiting resistor coupled between the negative terminal of the charger (i.e., the external input voltage terminal PACKN) and the charger detection port (CGRD terminal).
When the positive input terminal of the operational amplifier OP1 detects that the voltage of the charger detection port CGRD is negative (less than GND), the potential of the output terminal OPO of the amplifier OP1 drops, and for the PMOS transistor M1, the grid voltage drops, so that the current I from VDD to CGRD is enabled to flowCGRIncreasing raises the CGRD potential, clamping the CGRD potential to the GND potential.
When the positive input end of the operational amplifier OP1 detects that the voltage of the charger detection port CGRD is larger than the voltage of the ground end GND, M1 is turned off, and the circuit does not clamp the CGRD and does not influence the normal operation of the port.
In one embodiment, R1 is selected according to PACKN most negative voltage to ensure that the maximum current flowing through R1 does not exceed the maximum current withstand of the IC internal PMOS transistor M1. The size of the PMOS tube is selected according to the driving capability, and when the CGRN is negative voltage, the M1 can provide current flowing on the R1, so that the negative feedback loop can work normally. Since the current for clamping the CGRD potential is from VDD, no charging current is generated to the battery.
In one embodiment, for any IC port which can input negative voltage, the voltage of the IC port can be clamped at a proper value by reasonably selecting the current limiting resistor and the size of the PMOS tube, so that the abnormal operation of a chip caused by the larger negative voltage appearing at the IC port is avoided, and the trickle charging current is reduced.
In summary, the present invention provides a novel negative voltage clamp circuit.
The negative voltage clamp circuit includes: PMOS pipe, first resistance and operational amplifier.
The lithium battery protection circuit is provided with a positive power source end, a grounding end, an external input voltage end and a charger detection port; one end of the first resistor is coupled with the detection port of the charger, and the other end of the first resistor is coupled with the external input voltage end; the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is smaller than the voltage of the ground end, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is greater than the voltage of the ground end, the output end of the operational amplifier controls the PMOS tube to be closed, and the negative voltage clamping circuit does not clamp the charger detection port and does not influence the normal work of the charger detection port.
In one embodiment, a battery pack may be coupled between the positive power terminal and the ground terminal, and a charger may be coupled between the positive power terminal and the external input voltage terminal; the clamp current is sourced from the positive power supply terminal to ensure that no charging current is generated to the battery pack.
In one embodiment, the resistance of the first resistor is selected according to the most negative voltage of the external input voltage end, so that the maximum current flowing through the first resistor does not exceed the maximum current endurance of the PMOS transistor.
In one embodiment, the size of the PMOS transistor is selected according to the driving capability, so that when the detection port of the charger is under negative voltage, the PMOS transistor provides current flowing through the first resistor, and the negative feedback loop can be guaranteed to work normally.
The invention also provides a lithium battery protection circuit.
The lithium battery protection circuit is provided with a positive power supply terminal, a grounding terminal, an external input voltage terminal and a charger detection port, wherein the positive power supply terminal and the external input voltage terminal are coupled with a charger, and the positive power supply terminal and the grounding terminal are coupled with a battery pack.
The lithium battery protection circuit comprises a negative voltage clamping circuit, and the negative voltage clamping circuit comprises: PMOS pipe, first resistance and operational amplifier.
One end of the first resistor is coupled with the detection port of the charger, and the other end of the first resistor is coupled with the external input voltage end; the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is smaller than the voltage of the ground end, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end.
When the positive input end of the operational amplifier detects that the voltage value of the charger detection port is greater than the voltage of the ground end, the output end of the operational amplifier controls the PMOS tube to be closed, and the negative voltage clamping circuit does not clamp the charger detection port and does not influence the normal work of the charger detection port.
In one embodiment, the clamp current is sourced from the positive power supply terminal to ensure that no charging current is generated to the battery pack.
In one embodiment, the resistance value of the first resistor is selected according to the most negative voltage of the external input voltage terminal PACKN, so that the maximum current flowing through the first resistor does not exceed the maximum current tolerance of the PMOS transistor.
In one embodiment, the size of the PMOS transistor is selected according to the driving capability, so that when the detection port of the charger is under negative voltage, the PMOS transistor provides current flowing through the first resistor, and the negative feedback loop can be guaranteed to work normally.
The invention also provides a lithium battery protection circuit.
The lithium battery protection circuit is provided with a positive power supply terminal, a grounding terminal, an external input voltage terminal and a charger detection port, wherein the positive power supply terminal and the external input voltage terminal are coupled with a charger, and the positive power supply terminal and the grounding terminal are coupled with a battery pack;
the lithium battery protection circuit comprises a negative voltage clamping circuit, and the negative voltage clamping circuit comprises: feedback circuit, clamping circuit and first resistance.
The first resistor is coupled between the external input voltage terminal and the charger detection port.
The negative feedback circuit detects the voltage value of the detection port of the charger, and when the voltage value is lower than the voltage of the ground end, the negative feedback circuit outputs a clamping control signal to control the clamping circuit to generate clamping current.
The clamping circuit is coupled between the positive power supply end and the charger detection port, and generates the clamping current after receiving the clamping control signal of the negative feedback circuit, so that a voltage drop is formed on the first resistor, and the voltage of the charger detection port is clamped to the voltage of the ground end, so that the charger detection port is ensured not to generate negative voltage.
In one embodiment, the feedback circuit comprises a PMOS transistor. The clamping circuit comprises an operational amplifier. The grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
The negative voltage clamping circuit and the lithium battery protection circuit IC integrated with the negative voltage clamping circuit clamp external negative voltage by using a negative feedback technology, and simultaneously clamp current is extracted from a power supply, so that trickle charging current is reduced while the lithium battery protection circuit IC is not influenced by the negative voltage.
The terms and expressions which have been employed herein are used as terms of description and not of limitation. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.
Also, it should be noted that although the present invention has been described with reference to the current specific embodiments, it should be understood by those skilled in the art that the above embodiments are merely illustrative of the present invention, and various equivalent changes or substitutions may be made without departing from the spirit of the present invention, and therefore, it is intended that all changes and modifications to the above embodiments be included within the scope of the claims of the present application.

Claims (10)

1. A negative voltage clamp circuit integrated in a lithium battery protection circuit, the negative voltage clamp circuit comprising:
the PMOS tube, the first resistor and the operational amplifier;
the lithium battery protection circuit is provided with a positive power source end, a grounding end, an external input voltage end and a charger detection port; one end of the first resistor is coupled with the detection port of the charger, and the other end of the first resistor is coupled with the external input voltage end; the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled with the charger detection port, and the negative input end of the operational amplifier is coupled with the grounding end;
when the positive input end of the operational amplifier detects that the voltage value of the charger detection port is smaller than the voltage of the ground end, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and a voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end;
when the positive input end of the operational amplifier detects that the voltage value of the charger detection port is greater than the voltage of the ground end, the output end of the operational amplifier controls the PMOS tube to be closed, and the negative voltage clamping circuit does not clamp the charger detection port and does not influence the normal work of the charger detection port.
2. The negative voltage clamp circuit of claim 1, wherein a battery pack is coupled between the positive power supply terminal and the ground terminal, and a charger is coupled between the positive power supply terminal and the external input voltage terminal; the clamp current is sourced from the positive power supply terminal to ensure that no charging current is generated to the battery pack.
3. The negative voltage clamp circuit of claim 1, wherein the resistance of the first resistor is selected according to a most negative voltage of the external input voltage terminal to ensure that a maximum current flowing through the first resistor does not exceed a maximum current tolerance of the PMOS transistor.
4. The negative voltage clamp circuit of claim 1, wherein the size of the PMOS transistor is selected according to a driving capability, such that the PMOS transistor provides a current flowing through the first resistor when the charger detection port is under a negative voltage to ensure that the negative feedback loop operates normally.
5. In a lithium battery protection circuit, its characterized in that:
the lithium battery protection circuit is provided with a positive power supply terminal, a grounding terminal, an external input voltage terminal and a charger detection port, wherein the positive power supply terminal and the external input voltage terminal are coupled with a charger, and the positive power supply terminal and the grounding terminal are coupled with a battery pack;
the lithium battery protection circuit comprises a negative voltage clamping circuit, and the negative voltage clamping circuit comprises:
the PMOS tube, the first resistor and the operational amplifier;
one end of the first resistor is coupled with the detection port of the charger, and the other end of the first resistor is coupled with the external input voltage end; the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the charger detection port; the positive input end of the operational amplifier is coupled with the charger detection port, and the negative input end of the operational amplifier is coupled with the grounding end;
when the positive input end of the operational amplifier detects that the voltage value of the charger detection port is smaller than the voltage of the ground end, the output end of the operational amplifier outputs a clamping control signal to control the PMOS tube to generate clamping current, and a voltage drop is formed on the first resistor so as to clamp the voltage of the charger detection port to the voltage of the ground end;
when the positive input end of the operational amplifier detects that the voltage value of the charger detection port is greater than the voltage of the ground end, the output end of the operational amplifier controls the PMOS tube to be closed, and the negative voltage clamping circuit does not clamp the charger detection port and does not influence the normal work of the charger detection port.
6. The lithium battery protection circuit of claim 5, wherein the clamping current is sourced from the positive power supply terminal to ensure that no charging current is generated to the battery pack.
7. The lithium battery protection circuit as claimed in claim 5, wherein the resistance of the first resistor is selected according to the most negative voltage of the external input voltage terminal PACKN, so as to ensure that the maximum current flowing through the first resistor does not exceed the maximum current tolerance of the PMOS transistor.
8. The lithium battery protection circuit as claimed in claim 5 wherein the size of the PMOS transistor is selected based on the driving capability so that when the detection port of the charger is under negative voltage, the PMOS transistor provides current flowing through the first resistor to ensure that the negative feedback loop operates normally.
9. A lithium battery protection circuit is characterized in that:
the lithium battery protection circuit is provided with a positive power supply terminal, a grounding terminal, an external input voltage terminal and a charger detection port, wherein the positive power supply terminal and the external input voltage terminal are coupled with a charger, and the positive power supply terminal and the grounding terminal are coupled with a battery pack;
the lithium battery protection circuit comprises a negative voltage clamping circuit, and the negative voltage clamping circuit comprises:
the circuit comprises a feedback circuit, a clamping circuit and a first resistor;
the first resistor is coupled between the external input voltage end and the charger detection port;
the negative feedback circuit detects the voltage value of the detection port of the charger, and when the voltage value is detected to be lower than the voltage of the ground end, the negative feedback circuit outputs a clamping control signal to control the clamping circuit to generate clamping current;
the clamping circuit is coupled between the positive power supply end and the charger detection port, and generates the clamping current after receiving the clamping control signal of the negative feedback circuit, so that a voltage drop is formed on the first resistor, and the voltage of the charger detection port is clamped to the voltage of the ground end, so that the charger detection port is ensured not to generate negative voltage.
10. The lithium battery protection circuit as claimed in claim 9, wherein:
the feedback circuit comprises a PMOS tube;
the clamping circuit comprises an operational amplifier;
the grid electrode of the PMOS tube is coupled with the output end of the operational amplifier, the source electrode of the PMOS tube is coupled with the positive power supply end, and the drain electrode of the PMOS tube is coupled with the detection port of the charger; the positive input end of the operational amplifier is coupled to the charger detection port, and the negative input end of the operational amplifier is coupled to the grounding end.
CN202110224474.4A 2021-03-01 2021-03-01 Negative voltage clamping circuit and lithium battery protection circuit comprising same Pending CN113013942A (en)

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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
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CN113013942A true CN113013942A (en) 2021-06-22

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101404406A (en) * 2008-07-15 2009-04-08 无锡华润上华科技有限公司 Lithium battery protection circuit
CN105005346A (en) * 2015-06-04 2015-10-28 中颖电子股份有限公司 Negative voltage clamping circuit
US20160303989A1 (en) * 2011-12-09 2016-10-20 Shenzhen Carku Technology Co., Ltd. Portable backup charger

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101404406A (en) * 2008-07-15 2009-04-08 无锡华润上华科技有限公司 Lithium battery protection circuit
US20160303989A1 (en) * 2011-12-09 2016-10-20 Shenzhen Carku Technology Co., Ltd. Portable backup charger
CN105005346A (en) * 2015-06-04 2015-10-28 中颖电子股份有限公司 Negative voltage clamping circuit

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